[index] add index on reports.action_taken

db/migrate/20210108123456_add_index_on_reports_action_taken.rb

@@ -0,0 +1,7 @@
+class AddIndexOnReportsActionTaken < ActiveRecord::Migration[5.2]
+  disable_ddl_transaction!
+
+  def change
+    add_index :reports, :action_taken, algorithm: :concurrently
+  end
+end